Methanol from oxidation

Aldehydes are easily oxidized to carboxylic acids under conditions of ozonide hydroly SIS When one wishes to isolate the aldehyde itself a reducing agent such as zinc is included during the hydrolysis step Zinc reduces the ozonide and reacts with any oxi dants present (excess ozone and hydrogen peroxide) to prevent them from oxidizing any aldehyde formed An alternative more modem technique follows ozone treatment of the alkene m methanol with reduction by dimethyl sulfide (CH3SCH3)... 

One possible route is to make formaldehyde direcdy from methane by partial oxidation. This process has been extensively studied (106—108). The incentive for such a process is reduction of raw material costs by avoiding the capital and expense of producing the methanol from methane. 

Methanol is not classified as carcinogenic, but can be acutely toxic if ingested 100—250 mL may be fatal or result in blindness. The principal physiological effect is acidosis resulting from oxidation of methanol to formic acid. Methanol is a general irritant to the skin and mucous membranes. Prolonged skin contact with methanol vapor or Hquid can cause dermatitis. Methanol vapor can cause eye and respiratory tract irritation, nausea, headaches, and dizziness. 

Chem Systems Inc. proposed a process in which ben2yl alcohol obtained by an undisclosed direct oxidation of toluene is homologated with synthesis gas to yield 2-phen5iethyl alcohol, which is then readily dehydrated to styrene (57). This process eliminates the intermediate formation of methanol from synthesis gas but does require the independent production of ben2yl alcohol. 

Although methanol from synthesis gas has been a large-scale industrial chemical for 70 years, the scientific basis of the manufacture apparently can stand some improvement, which was undertaken by Beenackers, Graaf, and Stamhiiis (in Gheremisinoff, ed., Handbook of Heat and Mass Transfer, vol. 3, Gulf, 1989, pp. 671—699). The process occurs at 50 to 100 atm with catalyst of oxides of Gii-Zn-Al and a feed stream of H2, GO, and GO2. Three reactions were taken for the process ... 

For example, carbon dioxide from air or ethene nitrogen oxides from nitrogen methanol from diethyl ether. In general, carbon dioxide, carbon monoxide, ammonia, hydrogen sulfide, mercaptans, ethane, ethene, acetylene (ethyne), propane and propylene are readily removed at 25°. In mixtures of gases, the more polar ones are preferentially adsorbed). 

Extraction of luciferin with methanol from Cypridina frozen with dry ice. The chunks of frozen Cypridina are crushed into small pieces, and extracted with methanol with stirring. Small pieces of dry ice are added as needed to keep the temperature slightly below 0°C and also to prevent the oxidation of luciferin in a CO2 atmosphere. Luciferin is easily extracted into methanol. The mixture is filtered on a Buchner funnel (with suction), protecting the luciferin in a CO2 atmosphere by addition of small pieces of dry ice as needed. 

Mesoporous carbon materials were prepared using ordered silica templates. The Pt catalysts supported on mesoporous carbons were prepared by an impregnation method for use in the methanol electro-oxidation. The Pt/MC catalysts retained highly dispersed Pt particles on the supports. In the methanol electro-oxidation, the Pt/MC catalysts exhibited better catalytic performance than the Pt/Vulcan catalyst. The enhanced catalytic performance of Pt/MC catalysts resulted from large active metal surface areas. The catalytic performance was in the following order Pt/CMK-1 > Pt/CMK-3 > Pt/Vulcan. It was also revealed that CMK-1 with 3-dimensional pore structure was more favorable for metal dispersion than CMK-3 with 2-dimensional pore arrangement. It is eoncluded that the metal dispersion was a critical factor determining the catalytic performance in the methanol electro-oxidation. 

Korzeniewski C, Childers CL. 1998. Formaldehyde yields from methanol electrochemical oxidation on platinum. J Phys Chem B 102 489-492. 

Zinc oxide has various uses but the most important is as co-catalyst with CuO supported on A1203 for low-pressure synthesis of methanol from methane.325... 

Fig. 4.5. Mass spectroscopic detection of carbon dioxide during methanol adsorbate oxidation and Sn(IV) injection. Porous Pt electrode, real area 12.3 cm2. Procedure after methanol adsorption at 0.4 V from 10 2 M 13CH3OH/0.5 M H2S04, the electrolyte was exchanged with 0.5 M H2S04, then potential step to 0J was applied and Sn(lV) was added. Dashed line no tin added.

Figure 3.35 Potential dependence or the ft) integrated band intensity of the linear COad< derived from methanol at 0,4 V vs. RHE in I M CH3OH/0.5M H SO and (2) the methanol electro-oxidation current observed after the adsorption of methanol at 0.4 V. From K. Kunimatsu, Berichte der Bunsen-Ceseiischaft jur Phy-sitcafische Chemie. 1900.94. 1025 1030-...

Figure 3.38 (a) Current-time transient during the adsorption of methanol from solution at 0.330 V vs, Pd/H in 0.01 M CH.,OH + 0.5 M H2SOA. (b> Cyclic voltammograrn showing the oxidation of the adsorbate after replacing the solution by pure supporting electrolyte. 10 mV s, same solution as in (a). From Iwasita et at. (1987). 

The cycloaddition of nitrile oxide 235 to the 4-iminobenzopyran-2-one 236 gave the fully conjugated 1,2,4-oxadiazole 238 directly, a reaction that most likely proceeds via loss of methanol from the intermediate 237 (Scheme 36) <1996JHC967>. Similarly, nitrile oxide 239 reacted with imine 240 to give the 1,2,4-oxadiazole 242 via the nonisolable intermediate 241 <2002PJC1137>. 

Methoxycarbonylformonitrile oxide is smoothly generated by 3 -elimination of methanol from E -N-methoxy-N-(methoxycarbonylmethylene)amine N-oxide, MeC>2CCH=N(0Me)0, in the presence of a catalytic amount of boron trifluoride etherate (96). 

More recently, the direct synthesis of methanol from methane, using metallic gold as catalyst, was reported, involving a purported CH3-Au intermediate. Selenic acid was used as a stoichiometric oxidant as it is known to oxidize gold metal. Moderate turnovers (30) were achieved (Equation (6)).14... 

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